Electrical penetrators are used to power subsea electric submersible pump (ESP) equipment, compressor stations and the like which pressurize hydrocarbons in oil well installations at seabed, and also in other applications, such as high pressure downhole electrical penetrations and other penetrations, to provide power to various types of subsea equipment, such as separation equipment, metering equipment and/or monitoring and safety equipment. The penetrator extends through the wall or bulkhead of the vessel in which the equipment is located, and is normally connected to power cables at one end for connecting the equipment to an external power source. Penetrators may be connect an electric line into an environment with well pressure or pressurized fluid or from an environment at large water depths. This creates an extreme environment for the connection or penetrator in terms of pressure, temperature, and high voltage. The penetrator must transfer power through the barrier as well as maintain a pressure barrier for both internal pressure and external pressure caused by for instance the depth in seawater.
Consequently, an electrical penetrator assembly should be capable of operating at high differential pressures and at elevated temperatures.
In a typical electrical penetrator, a one-piece or multi-piece electrical conductor extends through a bore in an insulating sleeve or body. The insulating sleeve, in turn, extends through a penetrator body or housing which is connected to the vessel through which the penetrator extends.
In high temperature and high pressure applications, the insulating sleeve is usually made of a ceramic material.
The sealing between the electrical conductor and the ceramic insulator, and between the ceramic insulator and the penetrator housing or body, should be designed to withstand loads associated with manufacturing, testing, storage, transportation and, ultimately, operation at elevated temperatures and high pressures.
Normally, the penetrator body is made from a corrosion resistant metal in order to be connected to a metal wall or a bulkhead of the equipment to be provided with the penetrator. This produces the problem of providing a robust and reliable seal between the metal penetrator housing and the ceramic insulating sleeve.
U.S. Pat. No. 8,287,295 discloses a brazing and welding technique for creating a seal between the electrical conductor and the ceramic insulator. However, the same technique is not suitable for creating a seal between the ceramic insulator and the penetrator housing. Creating such a seal is challenging. Elastomer or thermoplastic seals may not be an acceptable option for specific application and metal seals are difficult to implement for this application. Therefore, an alternative, reliable solution is needed.
According to one aspect of the present invention, an object of the invention is to provide a method of manufacturing a robust and reliable electrical penetrator assembly which is capable of withstanding high differential pressure and a wide range between minimum and maximum temperature.
According to another aspect of the present invention, an object of the invention is to provide an electrical penetrator assembly which comprises a robust and reliable seal between a sleeve assembly and the penetrator housing.
A further object is to provide an electrical penetrator assembly which is capable of withstanding high differential pressure and a wide range between minimum and maximum temperatures.
Yet a further object is to provide an electrical penetrator assembly which allows for a design which minimizes the space required to implement the seal between the sleeve assembly and the penetrator housing.